Intravenous ("IV") sets are widely used in the prior art to provide intravenous fluid communication with a patient. The prior art intravenous set includes a needle cannula for insertion into a vein of the patient. The needle cannula communicates with one end of a flexible plastic tube, while the opposed end of the tube is connectable to a flexible bag or bottle containing a fluid to be administered to the patient.
A prior art intravenous set may also include a fitting to which a hypodermic syringe may be used for administering parenteral drugs to a patient. One example of such a fitting is known as a "straight-site." As depicted in FIG. 1, a straight site 10 is a relatively straight fitting, typically made from a plastic material, and includes an injection inlet 12 carrying medication from a source and an outlet portion 14 affixed to a tube 16 which delivers the parenteral drug to the patient. The injection inlet 12 usually includes a diaphragm portion 18, typically made of a rubber or similar compound, which can be pierced by the needle cannula of the syringe carrying the parenteral drug. The diaphragm portion 18, normally configured to be fitted in a fluid-tight manner to the injection inlet, typically defines a lip portion 20 which protrudes from the surface of the injection inlet along the outer circumference of the injection inlet.
A second example of an IV fitting is known in the art as a "Y-site." Referring to FIG. 2, a Y-site 22 is typically a Y-shaped plastic fitting having an inlet leg 24, an outlet leg 26, and an injection leg 28. Like the straight site fitting, the injection leg 28 of the Y-site 22 is also covered by a diaphragm 18 defining a lip portion 20. The diaphragm 18 can be pierced by the needle cannula of a syringe carrying the parenteral drug. The injection leg 28 and the outlet leg 26 of the prior art Y-site typically are collinear with one another, while the inlet leg 24 typically is aligned at approximately 30.degree.-45.degree. to the injection leg.
In use, a needle cannula of a hypodermic syringe carrying the parenteral drug to be administered is pierced through the membrane or septum 18 of the injection inlet of the straight site (FIG. 1) or injection leg of the Y-site (FIG. 2). The hypodermic syringe is used in the standard manner to inject a selected dose of the parenteral drug into the injection leg. The drug is then transported to the patient by the fluid flowing from the injection inlet (or leg) and through the outlet portion (or leg) and toward the patient. A hypodermic needle is often used for introducing medication through the septum. For purposes of illustration but not of limitation, as herein described the medication delivery is implemented through the septum using a syringe. However, it will be understood that the delivery is not so limited and that many fluid delivery devices can be used to provide fluid to the needle which pierces or passes through the septum.
As will be appreciated, the potential for accidental needle sticks is further reduced by prior art needle cannulas having a rigid generally cylindrical shield mounted concentrically around the needle cannula. The shield defines a diameter large enough to telescope over an injection inlet or leg on the intravenous set as the needle cannula enters the fitting. Some such shields are provided with at least one axial extending opening for receiving the inlet leg of a Y-site as remaining portions of the shield are telescoped over the injection leg. A protective shield of this general type is shown, for example, in U.S. Pat. No. Re. 33,617.
Although prior art protective shields, as described above, can reduce the probability of accidental needle sticks, the open end of the axially extending openings still offer a potential for contact with the needle cannula. The potential exists for accidental needlesticks caused by exposed needle cannula. The nurse or other medical personnel utilizing the shield must manually manipulate same to secure the shield to the injection inlet, oftentimes connecting the shield to the inlet with tape. Additionally, a source of intravenous fluid intended for connection to the intravenous fitting can be accidentally disengaged either before its initial use or between successive uses, thereby creating the potential both for contamination of the needle cannula and/or loss of medication, which can potentially be fatal to the patient.